Thermal Management System Vehicle and Method for Operating Two Cooling Circuits of a Thermal Management System

ABSTRACT

A thermal management system, for use in a vehicle, is provided in which coolant flows two cooling circuits can be mixed with each other as needed by a multi-way valve at an interface between a first cooling circuit for a battery and a second cooling circuit for an electric motor for driving the vehicle.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a U.S. national stage of International application No.PCT/EP2020/070250, filed on Jul. 17, 2020, which claims priority toGerman Application No. 10 2019 210 576.9 filed Jul. 17, 2019, thecontent of each of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to a thermal management system for use in avehicle. The invention also relates to a vehicle with such a thermalmanagement system. The invention also relates to a method for operatingtwo cooling circuits of such a thermal management system.

2. Description of the Related Art

A vehicle should be understood here as meaning any type of vehicle whichhas at least one first cooling circuit for controlling the temperatureof a battery and at least one second cooling circuit for controlling thetemperature of an electric motor and power electronics. This may be apartially electric or fully electric vehicle, but in particularpassenger cars and/or utility vehicles.

In such vehicles, two separate cooling or water circuits are required. Afirst cooling or water circuit is operated at a lower temperature forcontrolling the temperature of the battery, while a second cooling orwater circuit is operated at a higher temperature for controlling thetemperature of the electric motor and power electronics. Complex controlstrategies are responsible for ensuring that the components are heatedup to their optimal temperature as quickly as possible withoutsubsequently overheating during operation.

A thermal management system of the type described above is known from EP2392486 B1.

SUMMARY OF THE INVENTION

It is an object of the invention to improve such a thermal managementsystem.

This object may be achieved by a thermal management system for use in avehicle, wherein the thermal management system comprises a first coolingcircuit for a battery and a second cooling circuit for an electric motorfor driving the vehicle. The two cooling circuits are connected to eachother here in series by a multi-way valve in a first mode of the systemand in a first valve position of the multi-way valve (series connectionmode) or in parallel in a second mode of the system and in a secondvalve position of the multi-way valve (parallel connection mode).

In one aspect, in a third mode of the system and in a third valveposition, the multi-way valve takes up an intermediate position in whichthe coolant flows of the two cooling circuits are mixed with each otheras needed (needs-based mixing mode).

With such needs-based mixing, waste heat or heat loss from the electricmotor cooling circuit can advantageously be dissipated to the batterycooling circuit without a sudden transition behavior of the system beingexperienced, the transition behavior arising as such when switchingbetween the series connection mode and the parallel connection mode andbeing expressed in the form of sudden changes in temperature andpressure. In addition, frequent switching between the series connectionmode and the parallel connection mode can be avoided during transientjourneys in which the electric motor heats up quickly.

Such a needs-based mixing accordingly improves the temperature controlof both the electric motor cooling circuit and the battery coolingcircuit.

In another aspect, the third valve position can be set from a pluralityof possible intermediate positions. The individual intermediatepositions can be set in increments (or discontinuously) or infinitelyvariably (or continuously). An infinitely variable setting capabilityassists the temperature control of both the electric motor coolingcircuit and the battery cooling circuit.

In one aspect, the multi-way valve can be configured in the form of a4/2-way valve. A further multi-way valve is provided in the secondcooling circuit (or electric motor cooling circuit) downstream of theelectric motor, which conducts a coolant flow optionally via a path witha radiator or a radiator path and/or via a path parallel thereto, orbypass path, for bypassing the radiator. The further multi-way valve canalso be set in increments or infinitely variably into a plurality ofpossible positions—i.e., end and intermediate positions. The furthermulti-way valve can be configured in the form of a 3/2-way valve.

In another aspect, the multi-way valve can be configured in the form ofa 5/3-way valve, which is fluidically connected to a bypass path of thesecond cooling circuit (or electric motor cooling circuit) for bypassinga radiator and to a path parallel thereto with a radiator, or radiatorpath, wherein the bypass path and the radiator path originate from ajunction downstream of the electric motor.

In another aspect, a vehicle is provided with a thermal managementsystem of the previously described type.

In another aspect, a method for operating two cooling circuits of athermal management system of the previously described type is provided,in which a first cooling circuit is provided for a battery and a secondcooling circuit for an electric motor for driving the vehicle. The twocooling circuits are connected to each other here in series by amulti-way valve in a first mode of the system and in a first valveposition of the multi-way valve or in parallel in a second mode of thesystem and in a second valve position of the multi-way valve.

In another aspect, in a third mode of the system and in a third valveposition, the multi-way valve is switched into an intermediate positionin which the coolant flows of the two cooling circuits are mixed witheach other as needed.

The third valve position is set from a plurality of possibleintermediate positions. The individual intermediate positions can be setin increments or infinitely variably.

In a first aspect, a 4/2-way valve is used as the multi-way valve. Afurther multi-way valve is used in the second cooling circuit (orelectric motor cooling circuit) downstream of the electric motor,through which a coolant flow is optionally conducted via a path with aradiator, or radiator path, and/or via a path parallel thereto, orbypass path, for bypassing the radiator. The further multi-way valve canalso be set here in increments or infinitely variably into a pluralityof possible positions—i.e., end and intermediate positions. A 3/2-wayvalve can be used here for the further multi-way valve.

In an alternative second aspect, a 5/3-way valve is used as themulti-way valve, which is fluidically connected to a bypass path of thesecond cooling circuit (or electric motor cooling circuit) for bypassinga radiator, and to a path parallel thereto with a radiator, or radiatorpath, wherein the bypass path and the radiator path originate from ajunction downstream of the electric motor.

A fourth mode and/or a fifth mode of the system can advantageously alsobe set by the first aspect or the second aspect. In the fourth mode (orbypass mode) of the system, the radiator path can be bypassed forheating the battery. In the fifth mode of the system, by contrast, thebattery circuit can be cooled via the radiator path in order to avoidoverheating of the battery.

A computer program for carrying out the method described above is alsoproposed. The computer program can be read from a computer readablemedium into control electronics or a control unit and then used tocontrol the thermal management system accordingly.

The control electronics system here can have a digital microprocessorunit (CPU) connected in terms of data to a storage system and to a bussystem, a random access memory (RAM) and also a storage. The CPU isconfigured to execute commands, which are embodied as a program storedin a storage system, to detect input signals from the data bus and tooutput signals to the data bus. The storage system can have variousstorage media in the form of magnetic, solid-state and othernon-volatile media on which a corresponding computer program forcarrying out the method and the advantageous configurations is stored.The program can be configured such that it embodies or is able toexecute the methods described here such that the CPU can execute thesteps of such methods and thus control the thermal management system.

In addition, a computer-readable medium storing a computer programproduct is proposed, comprising program code which are stored on thecomputer-readable data storage medium in order to carry out the methoddescribed above when the program code is executed on a computer or in aCPU.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained below in detail with reference toillustrations in figures. Further advantageous developments of theinvention are apparent from the dependent claims and the descriptionbelow of preferred embodiments. For this purpose, in the figures:

FIG. 1 shows a thermal management system in a proposed first embodiment;

FIG. 2 shows an extract from the thermal management system shown in FIG.1;

FIG. 3 shows a thermal management system in a proposed secondembodiment;

FIG. 4 shows a first and second illustration of volume flows at a4/2-way valve of the proposed first embodiment;

FIG. 5 shows a third illustration of volume flows at a 3/2-way valve ofthe first embodiment;

FIG. 6 shows a first and second illustration of volume flows at a5/3-way valve of the proposed second embodiment; and

FIG. 7 shows a third illustration of volume flows at the 5/3-way valveof the second embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The thermal management system 2 according to FIG. 1 and FIG. 2illustrates a first cooling circuit 4 for a battery 10 and a secondcooling circuit 6 for an electric motor 12 for driving the vehicle, aswell as a refrigerant circuit 8 of an air conditioning system. Thevehicle can be, for example, a battery electric vehicle (BatteryElectric Vehicle, for short: BEV), a hybrid electric vehicle (HybridElectric Vehicle, for short: HEV) or a fuel cell vehicle (Fuel CellElectric Vehicle, for short: FCEV). These three different circuits 4, 6,8 merge to a certain extent with one another. The respective fluid isconveyed in the two cooling circuits 4, 6 by a dedicated electric pump16, 17.

The electric motor 12 and the power electronics LE should be operated ata coolant or cooling water temperature of approx. 85° C. The battery 10or the battery cells, by contrast, should be operated in a specificcoolant or cooling water temperature window between 20° C. and 40° C.because this ensures an optimal operating temperature range for thebattery 10. The temperature of the battery 10 or of the individualbattery cells themselves can definitely exceed the 40° C. temperaturethreshold. The two cooling circuits 4, 6 are therefore required. The twocooling circuits 4, 6 have to be able to both absorb and dissipate heat.While the battery cooling circuit 4 is cooled via a heat exchanger Ch(cf. FIG. 1; see chiller, for short: Ch) in relation to the refrigerantcircuit 8, the electric motor cooling circuit 6 can be cooled inrelation to the environment via a radiator 24 and in relation to thebattery cooling circuit 4 via a multi-way valve 14 described below(Coolant Flow Control Valve, for short: CFCV), wherein the multi-wayvalve 14 is an interface between the battery cooling circuit 4 and theelectric motor cooling circuit 6. The battery cooling circuit 4 can alsobe cooled via the radiator 24 in an appropriate valve position of themulti-way valve 14. However, since the battery coolant should not exceeda temperature of 40° C., the cooling via the radiator 24 is usuallyinsufficient, and therefore heat has to be dissipated via the heatexchanger Ch. In addition to the electric motor 12 and the powerelectronics LE, a charger (for short: C) is also to be cooled in theelectric motor cooling circuit 6. A temperature sensor CTS is providedfor controlling the respective cooling circuit 4, 6. A resistance heaterPTC is also provided in the battery cooling circuit 4. The electricmotor 12 is either water-cooled or oil-cooled. In the latter case, acorresponding oil cooling circuit of the electric motor 12 is connectedto the motor cooling circuit 6 by a heat exchanger (not shown).

The thermal management system 2 can be operated in different modes bythe multi-way valve 14. The multi-way valve 14 here is part of what isreferred to as an actuator or cooling water control valve, which as suchalso comprises a drive with an electric servomotor and a controller forthe electric servomotor.

In a first mode of the system (Use Case 1, for short: UC1=seriesconnection R with maximum heat recovery) and in a first valve positionof the multi-way valve 14, the cooling circuit 4 can be connected inseries with the cooling circuit 6. With respect to the multi-way valve14, coolant flows via an inlet or input a from the cooling circuit 6 viathe outlet or output c into the cooling circuit 4 and finally via theinlet or input d from the cooling circuit 4 via the outlet or output bback into the cooling circuit 6.

This series connection causes the battery cooling circuit 4 to heatrapidly, utilizing the waste heat from the electric motor 12 and thepower electronics LE. The electric motor cooling circuit 6 thus also hasthe function of a heating circuit.

In a second mode of the system (Use Case 2, for short: UC2=parallelconnection P with overheating protection) and in a second valve positionof the multi-way valve 14, the cooling circuit 4 can be connectedparallel to the cooling circuit 6, such that the two cooling circuits 4,6 are fluidically separated from each other. This separation protectsthe battery 10 from overheating.

In addition, a third mode of the system (Use Case 3, for short:UC3=mixing mode M with selective heat recovery) is also proposed, inwhich the multi-way valve 14 is switched to an intermediateposition—i.e., a third valve position—in which the coolant flows of thetwo cooling circuits 4, 6 are mixed with each other as needed.

Such a mixing mode allows both the temperature of the battery 10 and thetemperature of the electric motor 12 to be controlled more precisely.There are no high pressure and temperature jumps in the two coolingcircuits 4, 6, since there is no switching between the series connectionmode R and the parallel connection mode.

In a first embodiment (cf. FIG. 1 and FIG. 2), the multi-way valve 14 isdesigned in the form of a 4/2-way valve, via which the previouslydescribed system modes and valve positions can be set or controlled.Here, in the cooling circuit 6 downstream of the electric motor 12, afurther multi-way valve 18 in the form of a 3/2-way valve is alsoprovided, the outlet or output of which a^(I) is fluidically connectedto the inlet or input a of the 4/2-way valve 14. The multi-way valve 18is also part of a further actuator or cooling water control valve, whichas such also comprises a drive with an electric servomotor and acontroller for controlling the electric servomotor.

By the 3/2-way valve 18, a coolant flow can optionally be conducted viaa path 22 with a radiator 24 and/or via a path 20 parallelthereto—bypass path 20—for bypassing the radiator 24.

FIG. 4 illustrates the volume flows VS, which can be set with respect tothe 4/2-way valve of the first embodiment. The input a and the twooutputs b, c are seen here on the left of the graph. By contrast, inputd and the two outputs b, c are seen on the right of the graph. In thetwo graphs, a left and right area are each shown without a significantchange in terms of the volume flows. The left area describes the UC1mode or the series connection R. The right area, on the other hand,describes the UC2 mode or the parallel connection P.

Between these two modes, a middle area with a multiplicity ofintermediate positions of the valve 14 can be controlled so as to bringabout a needs-based mixing of the coolant flows of the cooling circuits4, 6 (mixing mode M=UC3). In principle, discrete intermediate positionscan be set in increments. As an alternative thereto, the intermediatepositions can also be set, however, infinitely variably or continuouslyover the entire middle area to enable even more precise control of thetemperature both of the battery 10 and the electric motor 12.

In an alternative second embodiment (cf. FIG. 3), the multi-way valve 14is configured in the form of a 5/3-way valve. An inlet or input e of the5/3-way valve that protrudes from the plane in FIG. 3 should also beimagined here, which inlet or input as such is fluidically connected viaa bypass path 20 to a junction KP (or the outlet a′ thereof) downstreamof the electric motor 12, wherein both the bypass path 20 and a path 22parallel thereto with a radiator 24 originate from the junction KP. Theradiator path 22 fluidically connects the junction KP (or the outlet c′thereof) to the inlet or input a of the 5/3-way valve.

FIG. 6 illustrates—analogously to FIG. 4—the volume flows VS which canbe set with respect to the 5/3-way valve of the second embodiment. Theinput a and the two outputs b, c are seen here on the left of the graph.By contrast, input d and the two outputs b, c are seen on the right ofthe graph. Also in these two graphs, a left and right area are eachillustrated without a significant change in terms of the volume flows.The left area describes the UC1 mode or the series connection R. Theright area, on the other hand, describes the UC2 mode or the parallelconnection P.

Between these two modes, a middle area with a multiplicity ofintermediate positions of the valve 14 can be controlled in order tobring about a needs-based mixing of the coolant flows of the coolingcircuits 4, 6 (mixing mode M=UC3). Analogously to what has been statedabove, discrete intermediate positions can in principle be set inincrements. As an alternative thereto, the intermediate positions canalso be set infinitely variably or continuously over the entire middlearea in order to enable even more precise control of the temperatureboth of the battery 10 and the electric motor 12.

With regard to the two proposed embodiments, the additional path 20makes it possible, in a corresponding valve position of the 3/2-wayvalve 18 (according to the first embodiment) or in a corresponding valveposition of the 5/3-way valve (according to the second embodiment), toset a fourth mode of the system (Use Case 4, for short: UC4=bypass modeB with reduction of the hydraulic resistance & maximum heat recovery),in which a hydraulic resistance is reduced and at the same time amaximum heat recovery for heating the battery 10 is made possible.

Via the path 22, however, in addition or as an alternative thereto, itis possible, in a corresponding valve position of the 3/2-way valve 18(first embodiment) or of the 5/3-way valve (second embodiment), to set afifth mode of the system (Use Case 5, for short: UC5=selectiveoverheating protection), in which overheating of the battery 10 isavoided by cooling via the radiator 24.

The graph in FIG. 5 illustrates the volume flows VS that can be set withrespect to the 3/2-way valve of the first embodiment, whereas the graphin FIG. 7 illustrates the volume flows VS that can be set with respectto the 5/3-way valve of the second embodiment. In FIG. 5, the input b′and the two outputs a′, c′ of the 3/2-way valve are seen. In FIG. 7,however, the volume flows VS through the inputs a, e of the 5/3-wayvalve are described, specifically based on the volume flow VS throughthe inlet b′ to the junction KP downstream of the electric motor 12, atwhich junction the bypass path 20 and the radiator path 22 originate.

The graph in FIG. 7 is compressed in relation to the graph in FIG. 5.This is because, in the case of the second embodiment, there is nosecond, separate multi-way valve which can be switched independently ofthe first multi-way valve. In this respect, there is to a certain extentno degree of freedom of adjustment with regard to FIG. 7, and thereforeclosing input a is accompanied by opening input e, and vice versa.

Although exemplary embodiments are explained in the above description,it should be noted that numerous modifications are possible. It shouldbe noted, furthermore, that the exemplary embodiments are merelyexamples which are in no way intended to limit the scope of protection,the applications, and the design. Instead, the above description gives aperson skilled in the art a guideline for the implementation of at leastone exemplary embodiment, wherein various changes may be made,especially with regard to the function and arrangement of the integralparts described, without departing from the scope of protection as it isapparent from the claims and combinations of features equivalentthereto.

1-12. (canceled)
 13. A thermal management system (2) for use in avehicle, comprising: a first cooling circuit (4) for cooling a battery(10); and a second cooling circuit (6) for cooling an electric motor(12) configured to drive the vehicle, wherein the first and secondcooling circuits (4, 6) are connected to each other: (a) in series by amulti-way valve (14) in a first mode of the thermal management system(2) and in a first valve position of the multi-way valve (14), or (b) inparallel in a second mode of the thermal management system (2) and in asecond valve position of the multi-way valve (14), wherein, in a thirdmode of the thermal management system (2) and in a third valve position,the multi-way valve (14) is configured to take up an intermediateposition in which coolant flows of the first and second cooling circuits(4, 6) are mixed with each other as needed, wherein the multi-way valve(14) is configured as a 4/2-way valve, and wherein the thermalmanagement system (2) further comprises a further multi-way valve (18)in the second cooling circuit (6) downstream of the electric motor (12),the further multi-way valve (18) being configured to conduct a coolantflow optionally via a path (22) with a radiator (24) and/or via a bypasspath (20) parallel to the path (22) so as to bypass the radiator (24).14. The thermal management system (2) as claimed in claim 13, whereinthe further multi-way valve (18) is configured as a 3/2-way valve. 15.The thermal management system (2) as claimed in claim 13, wherein thethird valve position can be set from a plurality of possibleintermediate positions.
 16. The thermal management system (2) as claimedin claim 15, wherein the individual intermediate positions can be set inincrements or infinitely variably.
 17. A vehicle comprising the thermalmanagement system (2) as claimed in claim
 13. 18. A method for operatingthe first and second cooling circuits (4, 6) of the thermal managementsystem (2) as claimed in claim 13, the method comprising: cooling thebattery (10) using the first cooling circuit (4); cooling the electricmotor (12) using the second cooling circuit (6) to cool the electricmotor (12); connecting the first and second cooling circuits (4, 6) toeach other: in series by the multi-way valve (14) in the first mode ofthe thermal management system (2) and in the first valve position of themulti-way valve (14); or in parallel in the second mode of the thermalmanagement system (2) and in the second valve position of the multi-wayvalve (14); and switching the multi-way valve (14) in a third mode ofthe thermal management system (2) and in a third valve position, into anintermediate position in which the coolant flows of the first and secondcooling circuits (4, 6) are mixed with each other as needed, wherein the4/2-way valve is used as the multi-way valve (14) and wherein thefurther multi-way valve (18) is used in the second cooling circuit (6)downstream of the electric motor (12), through which the coolant flow isconducted optionally via the path (22) with the radiator (24) and/or viathe path (20) parallel thereto for bypassing the radiator (24).
 19. Themethod as claimed in claim 18, further comprising using a 3/2-way valveas the further multi-way valve (18).
 20. The method as claimed in claim18, wherein the third valve position is set from a plurality of possibleintermediate positions.
 21. The method as claimed in claim 20, whereinthe individual intermediate positions are set in increments orinfinitely variably.
 22. The method as claimed in one of claim 18,wherein a fourth mode (or bypass mode) and/or a fifth mode of the systemis set, wherein, in the fourth mode, coolant is conducted via the bypasspath (20) for heating the battery (10), whereas, in the fifth mode,coolant is conducted via the radiator path (22) for cooling the battery(10).
 23. A non-volatile computer readable medium storing a computerprogram which, when executed on a computer, controls carrying out themethod as claimed in claim 18.